If either of this morning’s ACNielsen or Newspoll for New South Wales had been released on its own, it would have been easier to dismiss as unbelievable.

Instead, each reinforces the message, and it’s bad news for Peter Debnam’s opposition.

Nielsen puts Labor in the lead 57-43, a swing of just under 1% in its favour since the 2003 election. Newspoll goes further, 59-41, off a primary vote of 45% to 33%.

The best response Debnam could manage was: “I can’t explain the polls and I wouldn’t attempt to”. ALP state secretary Mark Arbib was holding out defiantly against overconfidence, saying “Our research … shows the election on a knife edge.”

A quick recap of recent state results will help put these polls in perspective. From 1995 to 2002, every state narrowly elected a new Labor government. Except for Western Australia (which had the most comfortable win to start with), every one of those governments was re-elected in a landslide.

Those landslide majorities have now been tested five times: twice in Queensland, and once each in NSW, Victoria and Tasmania. So far, they’ve held up very well. In terms of votes, the best opposition performance was a swing of almost 4% in Queensland in 2004. Last year’s Victorian election was a slightly smaller swing, but a bigger gain of seats.

For state oppositions these days, that’s about as good as it gets. If the precedents hold, then Debnam, needing a swing (even with independents’ support) of 8.4%, was never going to be in the running.

Whether the ALP can actually get a swing in its favour is another question – it did, just slightly, in 2003, but it’s a much more tired looking government four years later.

Even so, the marginals on the Coalition side of the pendulum will now be the subject of renewed interest: Terrigal (formerly Gosford) on 0.6%, Murray-Darling (Labor-held, but notionally a Nationals seat after redistribution) on 1.4%, and maybe even South Coast (the only Liberal gain last time) on 1.6%.